The preparer of a National Register nomination collects, evaluates,
and presents the information required to document the property and
justify its historical significance. Among the decisions the preparer
must make is the selection of the property's boundaries: in addition
to establishing the significance and integrity of a property, the
physical location and extent of the property are defined as part of
the documentation. Boundary information is recorded in Section 10,
Geographical Data, on the National Register Registration Form. This
bulletin is designed to assist the preparer in selecting, defining,
and documenting boundaries for National Register properties. The bulletin
addresses the factors to consider and includes examples that illustrate
properly defined boundaries for a variety of property types.

WHY BOUNDARIES ARE IMPORTANT

Carefully defined boundaries are important for several reasons.
The boundaries encompass the resources that contribute to the property's
significance. Boundaries may also have legal and management implications.
For example, only the area within the boundaries may be considered
part of the property for the purposes of Federal preservation tax
incentives and charitable contributions. State and local laws that
require consideration of historic resources may also refer to boundaries
in the application of implementing regulations or design controls.
National Register boundaries, therefore, have legal implications that
can affect the property's future. Under Federal law, however, these
considerations apply only to government actions affecting the property;
National Register listing does not limit the private owner's use of
the property. Private property owners can do anything they wish with
their property, provided no Federal license, permit, or funding is
involved.

Under Section 106 of the National Historic Preservation Act of 1966,
as amended, Federal agencies must take into account the effect of
their actions on historic properties (defined as properties in, or
eligible for, the National Register of Historic Places) and give the
Advisory Council on Historic Preservation the opportunity to comment.
To be in compliance with the act, Federal agencies must identify and
evaluate National Register eligibility of properties within the area
of potential effect and evaluate the effect of the undertaking on
eligible properties.

The area of potential effect is defined as the area in which eligible
properties may be affected by the undertaking, including direct effects
(such as destruction of the property) and indirect effects (such as
visual, audible, and atmospheric changes which affect the character
and setting of the property). The area of potential effect may include
historic properties that are well beyond the limits of the undertaking.
For example, a Federal undertaking outside of the defined boundaries
of a rural traditional cultural property or an urban historic district
can have visual, economic, traffic, and social effects on the setting,
feeling, and association of the eligible resources.

Large properties present special problems. For example, an undertaking
in a narrow corridor, such as a pipeline, may affect part of a large
archeological site, traditional cultural property, or rural historic
district. Such properties may extend far beyond the area of potential
effect or access may be denied in areas beyond the undertaking. It
is always best to consider the entire eligible property, but it may
not be possible or practical to define the full extent of the property.
In such cases, reasonable, predicted, estimated, or partial boundaries
encompassing resources within the area of potential effect may be
the only way to set the limits of contributing resources when the
entire property cannot be observed or evaluated from historic maps
or other documents (as in the case of subsurface archeological resources).
Consider all available information and select boundaries on the basis
of the best information available. When defining boundaries of large
resources extending beyond the area of potential effect, it is advisable
to consult the State historic preservation office.

GETTING HELP

In addition to the guidance in this bulletin, assistance is also
available from State Historic Preservation Officers, Federal Preservation
Officers, and the staff of the National Register of Historic Places.
These professionals can help preparers with general questions and
special problems. For assistance with specific questions or for information
on how to contact the appropriate State Historic Preservation Officer
or Federal Preservation Officer, contact the National Register of
Historic Places, National Register, History and Education, National
Park Service, 1849 C Street, NW, Washington, D.C. 20240.

Several other National Register publications are also available to assist
preparers. National Register Bulletin:
How to Complete the National Register Registration Form provides
the basic instructions for boundary selection and documentation. The
following instructions, which are consistent with those in How
to Complete the National Register Registration Form, provide additional
assistance for the preparer. The following discussion addresses many
property types by considering the special boundary problems associated
with each type and providing case studies to assist the preparer in
dealing with such issues. Bulletins that deal with specific property
types may also be useful (see the list of National Register Bulletins
at the end of this publication).

DECIDING WHAT TO INCLUDE

Selection of boundaries is a judgment based on the nature of the
property's significance, integrity, and physical setting. Begin to
consider boundaries during the research and data-collection portion
of the nomination process. By addressing boundary issues during the
field and archival research, the preparer can take into account all
the factors that should be considered in selecting boundaries. When
significance has been evaluated, reassess the boundaries to ensure
appropriate correspondence between the factors that contribute to
the property's significance and the physical extent of the property.

Select boundaries that define the limits of the eligible resources.
Such resources usually include the immediate surroundings and encompass
the appropriate setting. However, exclude additional, peripheral areas
that do not directly contribute to the property's significance as
buffer or as open space to separate the property from surrounding
areas. Areas that have lost integrity because of changes in cultural
features or setting should be excluded when they are at the periphery
of the eligible resources. When such areas are small and surrounded
by eligible resources, they may not be excluded, but are included
as noncontributing resources of the property. That is, do not select
boundaries which exclude a small noncontributing island surrounded
by contributing resources; simply identify the noncontributing resources
and include them within the boundaries of the property.

GUIDELINES FOR SELECTING BOUNDARIES:
ALL PROPERTIES

(summarized from How to Complete the National Register Registration
Form, p. 56)

Select boundaries to encompass but not exceed the extent
of the significant resources and land areas comprising the
property.

Include all historic features of the property, but do not
include buffer zones or acreage not directly contributing
to the significance of the property.

Exclude peripheral areas that no longer retain integrity
due to alterations in physical conditions or setting caused
by human forces, such as development, or natural forces, such
as erosion.

Include small areas that are disturbed or lack significance
when they are completely surrounded by eligible resources.
"Donut holes" are not allowed.

Define a discontiguous property when large areas lacking
eligible resources separate portions of the eligible resource.

Districts may include noncontributing resources, such as altered
buildings or buildings constructed before or after the period of significance.
In situations where historically associated resources were geographically
separated from each other during the period of significance or are
separated by intervening development and are now separated by large
areas lacking eligible resources, a discontiguous district may be
defined. The boundaries of the discontiguous district define two or
more geographically separate areas that include associated eligible
resources.

FACTORS TO CONSIDER

There are several factors to consider in selecting and defining
the boundaries of a National Register property. Compare the historic
extent of the property with the existing eligible resources and consider
integrity, setting and landscape features, use, and research value.

Integrity: The majority of the property must retain integrity
of location, design, setting, feeling, and association to be eligible.
The essential qualities that contribute to an eligible property's
significance must be preserved. Activities that often compromise
integrity include new construction or alterations to the resource
or its setting. Natural processes that alter or destroy portions
of the resource or its setting, such as fire, flooding, erosion,
or disintegration of the historic fabric, may compromise integrity.
For example, an abandoned farmhouse that has been exposed to the
elements through years of neglect may have lost its integrity as
a building; however, it may retain integrity as an archeological
site.

Setting and Landscape Features: Consider the setting and historically
important landscape features. Natural features of the landscape
may be included when they are located within the district or were
used for purposes related to the historical significance of the
property. Areas at the margins of the eligible resources may be
included only when such areas were historically an integral part
of the property. For example, a district composed of farmsteads
along a creek may include the creek if it runs through the district,
if the creek was important in the original siting of the farmsteads,
or if the creek was a source of water power or natural resources
exploited by the farmsteads. Consult National
Register Bulletin: Guidelines for Evaluating and Documenting Rural
Historic Landscapes for additional guidance in selecting
boundaries for rural historic landscapes.

Use: Consider the historic use of the property when selecting
the boundary. The eligible resource may include open spaces, natural
land forms, designed landscapes, or natural resources that were
integral to the property's historic use. Modern use may be different,
and some modern uses alter the setting or affect built resources.
The effect of such uses must be assessed in identifying resources
that retain integrity. For example, a Hopewell mound archeological
site now used as a golf course may retain integrity where the form
of the prehistoric earthworks has been preserved, but construction
of sand traps or other landscaping that altered landforms would
compromise integrity. A marsh that provides plant materials for
traditional basketmakers may retain integrity where it remains in
its natural wetland condition, but may have lost integrity where
it has been drained and cultivated.

Research Potential: For properties eligible under Criterion D,
define boundaries that include all of the resources with integrity
that have the potential to yield important information about the
past. Such information is defined in terms of research questions
to which the information pertains, and the property should include
the com-ponents, features, buildings, or structures that include
the information. For example, an eligible prehistoric longhouse
site should include longhouse features as well as associated pit
features, middens, and hearths. Geographically separate but historically
associated activity areas may also be included in the property even
when they are not adjacent to the main concentration of eligible
resources. For example, lithic procurement and processing loci that
were historically associated with a village site but geographically
separated from it may be included in a discon-tiguous district.
Remember that many properties eligible under other criteria include
contributing archeological resources that may yield important information
about the property. Consider the extent of associated archeological
resources when selecting boundaries.

SELECTING BOUNDARIES

Identify appropriate natural or cultural features that bound the
eligible resource. Consider historical and cartographic documentation
and subsurface testing results (for archeological resources) in addition
to existing conditions. Some boundaries can be directly observed by
examining the property; others must be identified on the basis of
research. Take into account the modern legal boundaries, historic
boundaries (identified in tax maps, deeds, or plats), natural features,
cultural features, and the distribution of resources as determined
by survey and testing for subsurface resources.

Owner objections may affect the listing of the entire property, but
not the identification of the boundaries. If the sole private owner
of a property or the majority of the private owners (for properties
with multiple owners) objects to listing, the property (with boundaries
based on an objective assessment of the full extent of the significant
resources) may be determined eligible for the National Register but
not listed.

Boundaries should include surrounding land that contributes to the
significance of the resources by functioning as the setting. This
setting is an integral part of the eligible property and should be
identified when boundaries are selected. For example, do not limit
the property to the footprint of the building, but include its yard
or grounds; consider the extent of all positive subsurface test units
as well as the landform that includes the archeological site; and
include the portion of the reef on which the vessel foundered as well
as the shipwreck itself.

Distribution of Resources: Use the extent of above-ground resources
and surrounding setting to define the boundaries of the property.
For archeological resources, consider the extent of above-ground
resources as well as the distribution of subsurface remains identified
through testing when defining the boundaries of the property.

Current Legal Boundaries: Use the legal boundaries of a property
as recorded in the current tax map or plat accompanying the deed
when these boundaries encompass the eligible resource and are consistent
with its historical significance and remaining integrity.

Historic Boundaries: Use the boundaries shown on historic plats
or land-ownership maps (such as fire insurance or real estate maps)
when the limits of the eligible resource do not correspond with
current legal parcels.

Natural Features: Use a natural feature, such as a shoreline,
terrace edge, treeline, or erosional scar, which corresponds with
the limit of the eligible resource.

Cultural Features: Use a cultural feature, such a stone wall,
hedgerow, roadway, or curb line, that is associated with the significance
of the property, or use an area of modern development or disturbance
that represents the limit of the eligible resource.

Selecting boundaries for some properties may be more complicated,
however. Consider and use as many features or sources as necessary
to define the limits of the eligible resource. In many cases, a combination
of features may be most appropriate. For example, the National Register
boundaries of a property could be defined by a road on the south,
a fence line on the west, the limits of subsurface resources on the
north, and an area of development disturbance on the east. Consider
map features or reasonable limits when obvious boundaries are not
appropriate.

Cartographic Features: Use large-scale topographic features,
contour lines, or section lines on United States Geographical Survey
maps to define the boundaries of large sites or districts.

Reasonable Limits: Use reasonable limits in areas undefined by
natural or cultural features. For example, define the boundary of
a property as 15 feet or 5 meters from the edge of the known resources,
or define a straight line connecting two other boundary features.
If a surveyed topographic map is available, select a contour line
that encompasses the eligible resources. Reasonable limits may also
be appropriate for a rural property when there is no obvious house
lot or natural or cultural feature to use. Be sure that an appropriate
setting is included within arbitrary boundaries, however, and explain
how the limits were selected.

REVISING BOUNDARIES

Boundaries for listed properties need to be revised when there are
changes in the condition of the resources or the setting. If resources
or setting lose integrity and no longer contribute to the significance
of the property, it is appropriate to revise the boundaries. Revisions
may also be appropriate for nominations prepared in the early years
of the National Register program, when nominations had limited or
vague boundary documentation. Follow the guidance presented in this
bulletin when revising boundary documentation.